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Commit 3e5b5016 authored by Takashi Iwai's avatar Takashi Iwai
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ALSA: pcm core - Avoid jiffies check for devices with BATCH flag 



The hardware devices with SNDRV_PCM_INFO_BATCH flag can't give the
precise current position.  And such hardwares have often big FIFO
in addition to the ring buffer, and it screws up the jiffies check
in pcm_lib.c.

This patch adds a simple check of info flag so that the driver skips
the jiffies check in snd_pcm_period_elapsed() when BATCH flag is set.

Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 2008f137

sound/core/pcm_lib.c

+7 −0
Original line number Diff line number Diff line
@@ -249,6 +249,12 @@ static int snd_pcm_update_hw_ptr_interrupt(struct snd_pcm_substream *substream) 
			new_hw_ptr = hw_base + pos;

		}

	}

	/* Skip the jiffies check for hardwares with BATCH flag.

	 * Such hardware usually just increases the position at each IRQ,

	 * thus it can't give any strange position.

	 */

	if (runtime->hw.info & SNDRV_PCM_INFO_BATCH)

		goto no_jiffies_check;

	hdelta = new_hw_ptr - old_hw_ptr;

	jdelta = jiffies - runtime->hw_ptr_jiffies;

	if (((hdelta * HZ) / runtime->rate) > jdelta + HZ/100) {
@@ -272,6 +278,7 @@ static int snd_pcm_update_hw_ptr_interrupt(struct snd_pcm_substream *substream) 
		hw_base -= hw_base % runtime->buffer_size;

		delta = 0;

	}

 no_jiffies_check:

	if (delta > runtime->period_size + runtime->period_size / 2) {

		hw_ptr_error(substream,

			     "Lost interrupts? "